This comic is much like the puzzles in the game Machinarium: Baffling at first, and then forehead-slappingly obvious once you already understand it.
Machinarium is a throwback to the point-and-click adventure games of old. The style is a kind of "Alice in Wonderland" meets "Scrapheap Challenge". People blame the fall of these kind of adventure games on the glut of low-quality titles and the rise of snazzy graphics technology. I think there's a lot of truth in that, but the other thing that hurt the genre is the internet itself.
Back in the day, if you got stuck on a puzzle: You stayed stuck. It didn't matter how many hours it took you to sort it out, you weren't going to proceed until you worked it out on your own. But being stuck for a couple of hours on the same puzzle wasn't actually all that fun. Once the internet arrived and puzzle-smashing knowledge was never more than a simple web search away, then these games became less about smarts and more about willpower.
Hmm. I've been stuck for fifteen minutes. Bored now. I'll just Google the answer. But now I'm just reading a FAQ and following directions, which defeats the entire point of the game. Why am I doing this again?
You can test your brainpower and your willpower by playing the Machinarium demo.